1. Field of Invention
This invention generally relates to a burner in which steam is utilized to atomize fluid fuels.
2. Prior Art
Oil burners are often mounted to fire through a tile chamber. The tile chamber serves as a secondary ignition device to prevent the relatively cold incoming fuel mixture from blowing the flame from the burner which produces an ignition failure, a condition known as blow off.
Tile chambers are undesirable as they increase the space requirement of a burner. In addition, heat is lost by radiation, the tiles deteriorate and the turndown ratio (maximum divided by minimum heat output) is limited. Turndown ratios of 2-1 to 3-1 are typical. The tiles also prevent burning of fuels which contain components which chemically attack the tiles.
Typically to change burner fuels from gas to oil or the reverse, requires replacing the fuel nozzle which can necessitate shutdown of the apparatus in which the burner is utilized.
In U.S. Pat. No. 2,863,499 a burner is taught which burns a variety of liquid fuels. The burner is operative only at high heat output and has a turndown ratio of maximum to minimum heat output of less than 2 to 1.
In U.S. Pat. No. 3,326,472 the burner of U.S. Pat. No. 2,863,499 is modified to allow use of gas as an alternative fuel. The modified burner introduces a gas-air mixture to the air tube of the unmodified burner of U.S. Pat. No. 2,863,499 by attaching to the air tube a gas line having specially designed apertures therein for admitting air. When burning gas the modified burner is susceptible to backfire through the apertures and blow off. The range of heat output with gas, when the burner is not susceptible to backfire or blow off, does not overlap the range of heat output with oil.
Control of burner flame configuration particularly in multiple hearth furnaces, is desireable to prevent melting of metal surfaces or hot spots.